The present invention relates to immunoassays for an analyte, such as a drug, hormone or an antigen, in a liquid sample, such as body fluid. More particularly, the present invention relates to a method for the detection of an analyte in a body fluid using anti-allotypic monoclonal antibodies as capture reagents or as detector reagents.
Many types of ligand-receptor assays have been used to detect the presence of various substances in body fluids such as urine or blood serum. These assays typically involve antigen-antibody reactions and synthetic conjugates comprising enzymatic, fluorescent, chemiluminescent, or radioactive labels. In most of these assays, there is a receptor (e.g. an antibody) which is specific for the selected ligand (e.g., analyte or antigen), and a means for detecting the presence and/or amount of the antigen-antibody reaction product. Most current tests are designed to make a quantitative determination, but in some circumstances all that is required is a positive/negative indication.
These immunoassays must be very sensitive because of the often small concentration of the ligand of interest in the test fluid. However, test samples of body fluids contain numerous components, some of which can interfere with the immunoassay. For example, endogenous immunoglobulins or complement proteins present in the sample may react with the test immunoglobulins, causing misleading results. Immunoglobulins or complement proteins present in the sample may react with capture antibodies, analyte-specific binding proteins (which can be primary antibodies) which are part of the immunoassay, thereby preventing attachment of the analyte to the binding protein, and/or attachment of the binding protein to the antibodies (which can either be labeled or attached to a solid phase). Additionally, complement proteins in the test sample may bind to analyte-antibody complexes formed during the test and prevent attachment of the binding proteins to the capture or labeled antibodies. When the assay results are read and interpreted, they may indicate an incorrectly high or low concentration of analyte, depending on the assay format used. Such incorrect results may lead a physician to improperly diagnose a disease state, or prescribe an incorrect course of treatment. Because of these problems, competitive immunoassays, sandwich immunoassays and other immunological detection methods utilize various techniques to reduce interferences. However, these techniques have not solved all of the problems encountered in these detection methods. It is an object of the present invention to provide an improved immunoassay having less sensitivity to endogenous components in the sample and greater accuracy and discrimination for analytes of interest.